The invention is directed to a conveying and/or storage container for radioactive materials which produce .gamma. and neutron radiation emissions and noteworthy residual heat, essentially consisting of a container body having shielding function for .gamma.-radiation, a neutron shielding and cooling fins whereby the neutron shielding is arranged between the bar shaped fins.
Containers which are employed for conveying and/or storing spent fuel elements must safely confine the radioactivity of the inserted material and demonstrate in strength tests that this is also guaranteed in extreme accident situations. However, simultaneously they must also shield off the gamma and neutron rays which are set free in the radioactive decay reactions and carry off the heat of decay to the outside.
Known shielding containers generally consist of a metallic base container with the required mechanical strength and the required wall thickness for shielding the gamma rays are customarily made of steel or a combination of lead and steel and an outer shell of neutron shielding material, generally small polyethylene spheres cast in synthetic resin.
Normally there are welded or soldered heat conducting bars or fins which penetrate the resin layer to the metallic base body. They are necessary for enlargement of the metallic surface in containers which are designed for a high thermal efficiency and for dissipating the heat through the generally poor heat conducting neutron shielding layer.
It is a disadvantage of these constructions that even slight collisions of the containers, which can occur even in routine operation, can lead to damage of the heat conducting fins and the resin layer and accordingly require an expensive repair of the entire container. Further disadvantageous situations appear in the purification and decontamination.
A further disadvantage of this known shielding container is that the thickness of the neutron shielding must be designed for the maximum planned conveyance, thus it is not variable.
This is also true for containers in which neutron absorbing material is accommodated in bores in the metallic base body.
In German OS No. 2065863 there is reported about neutron shielding molded pieces, inter alia wooden boards or corresponding hydrogen containing materials, in a given case injected with boron, whereby these molded pieces are located between the cooling fins and are clamped to the base body. Substantial disadvantages, however, are the combustibility, the variable water content in using wood, the unfavorable thermal conductivity and the limited neutron absorption properties. The decontamination is difficult. The gaps between the molded bodies and the cooling fins are typically inadmissible traps of contamination.
Therefore, it was the problem of the present invention to produce a container for radioactive materials, consisting essentially of a container body having a shielding function for .gamma.-radiation, a neutron shielding and cooling fins wherein the neutron shielding is arranged between the bar shaped cooling fins, in which the neutron shielding is protected and is variably adjustable, furthermore is favorable to the dissipation of heat and requires little maintenance while avoiding the described disadvantages.